Syphilis is a sexually transmitted disease (STD) caused by a type of bacteria called Treponema pallidum. Syphilis has made an astounding comeback in Seattle and King County. In the early 1990s, syphilis was almost eliminated in King County. Now, we see over 300 cases per year and 9 out of 10 infections are in gay and bi men. There are more new cases of syphilis each year than HIV! And syphilis rates are 15 times higher in gay/bi men who have HIV than in gay/bi men who do not have HIV.